1. Field of the Invention
This invention relates to medically sound procedures for reduction in environmental allergenicity due to certain airborne allergens known to produce asthma, allergic rhinitis and atopic eczema in both humans and animals. Specifically, allergens derived from house dust mites, certain molds, cockroaches, cats and dogs are removed from indoor living spaces to provide sanctuaries for asthma sufferers.
2. Review of Related Art
Asthmatic bronchitis (asthma), allergic rhinitis (hay fever), and atopic eczema are immunologic reactions which, in the majority of cases, are triggered by one or more allergens from five primary sources: cat dander, dog dander, mold spores, cockroach fecal pellets and house dust mite fecal pellets. All of the primary asthmatic allergens from these five sources are protein in nature, typically glycoprotein. These allergens accumulate on various indoor surfaces and in allergen reservoirs, such as carpets, upholstery, mattresses and pillows. The presence of these allergens in any interior space can make that space hazardous for an asthmatic patient.
Of the primary allergens, house dust mite (HDM) accounts for 50-55% of the asthmatic's problems. HDMs proliferate indoors when temperature, humidity and the presence of sloughed epithelial cells (the mite's primary food source) are adequate for their survival and reproduction. Adult HDMs produce 20-30 fecal pellets per day per mite over a life span of 2½ months. Each fecal pellet is heavily inoculated during its midgut formation with proteins (principally digestive enzymes) capable of evoking an immune response.
HDM allergenic proteins have been identified for mites of the genus Dermatophagoides, and the proteins fall mainly into two immunological groups: Der I (Der pI and Der fI) and Der II (Der pII and Der fII). The primary sequence of HDM allergens has been disclosed (see a series of U.S. patents and also reviews by Thomas, et al. (1998), “House-dust-mite allergens,” Allergy, 1998 September; 53(9):821-32; Platts-Mills TA, et al. (1997), “Indoor allergens and asthma: report of the Third International Workshop,” J Allergy Clin Immunol 1997 December; 100(6 Pt 1):S2-24; and Chua Ky., et al. (1996), “Analysis of sequence polymorphism of a major mite allergen, Der p 2,” Clin Exp Allergy. 1996 July; 26(7):829-37). HDMs are primarily found in indoor textiles (carpet, upholstery, mattresses and pillows) where their population can become enormous—well into the millions. Mechanical disturbance can release the proteins from dried fecal pellets into the air, producing an allergenic cloud that will resettle onto textile surfaces over time.
Mold spores account for 10-15% of asthmatic reactions, and four mold genera account for nearly all of the allergenic spores. These genera are: Alternaria, Cladiosporium, Aspergillus, and Penicillium, with Alternaria accounting for about 80% of the mold spore responses of asthmatics. Cat dander accounts for 10-15%, cockroaches account for 5-10%, and dog dander accounts for 5-10% of asthmatic reactions.
HDM, cockroach and mold allergens tend to be larger and heavier; therefore, they often settle on textile-covered surfaces, such as carpets and upholstery. Even after being disrupted, such as when a person walks on a carpet or sits on a sofa, the allergens will only rise up a few feet in the air (e.g., about three feet) and quickly settle again.
Cat and dog allergens, on the other hand, tend to be smaller and lighter; thus, they often “float” in the air for up to six months. Eventually, those allergens will attach to a surface, such as a textile-covered surface, wall or ceiling. However, once they are disrupted, the allergens will again “float” in the air for a lengthy period of time before settling.
Physicians currently address the disorders produced by allergens with symptomatic medicinal approaches, desensitization methods and preventive measures such as textile removal from the home, air filters, dehumidifiers, mattress covers and the like, yet the problem still exists. Ablative HDM chemicals currently in use include short term insecticides or denaturants that reduce the allergenicity of protein allergens, such as the proteins in HDM fecal pellets. Insecticides that have been tested include benzyl benzoate (U.S. Pat. Nos. 5,916,917; 6,107,341; and 6,117,440) phenyl salicylate, the organophosphate, pirimiphos methyl (Mitchell, et al., 1985, “Reduction of house dust mite allergen levels in the home: uses of the acaricide, pirimiphos methyl,” Clin. Allergy, 15:234), and synthetic pyrethroids such as permethrin (U.S. Pat. Nos. 5,843,981; 5,916,580; and 5,965,602; Glass, et al., “Evaluation of the acaricide permethrin against all stages of the American house dust mite Dermatophagoides farinae Hughes (Pyroglyphidae),” in Mitchell, et al., eds., Acarology IX Proceedings, Columbus, Ohio Biological Survey, 1997, pp. 693-695). International Publication No. WO 98/30236 discloses a pesticide using protease enzymes to kill insects for the purpose of decreasing or eliminating the incidence of allergic reaction to dust, but this reference does not address allergic reactions to the enzyme. Tannic acid has been used to denature HDM fecal pellets short term (Green, “Abolition of allergens by tannic acid,” Lancet, 2:160 1984; U.S. Pat. No. 4,977,142), and polyphenol denaturants have been used in combination with insecticides (Green, et al., 1989, “Reduction of house dust mites and mite allergens: Effects of spraying carpets and blankets with Allersearch DMS, an acaricide combined with an allergen reducing agent,” Clin. Exp. Allergy, 19:203; U.S. Pat. No. 4,806,526).
Either the insecticide treatments or the chemical denaturants must be reapplied at 2-3 month intervals for any hope of efficacy. These products are available over-the-counter, and are subject to the variability existing among do-it-yourselfers who apply such products. These products are also displaced from textiles during vacuuming and become air-borne, are inhaled, and can serve as a major irritant to asthmatics or hay fever sufferers. Therefore, there remains a need for improved methods of reducing allergenicity in indoor spaces to alleviate the suffering of asthmatics and hay fever sufferers.